Low temperature lubricants



Patented Oct. 16, 1 945 umreo STATES PATENT orrlce LOW LUBRICANTS John1). Morgan, South a N. 1., asslgnor to Cities Service Oil Company, NewYork, N. Y., a corporationof Pennsylvania No Drawing. Application August27, 1942,

Serial No. 456,366

11 Claims.

This invention relates to low temperature lubricants. More particularlythe invention relates to lubricants made from synthetic compounds whichhave proper physical properties for low temperature lubrication.

I have discovered that Decalin (Ciel-11a), decahydronaphthalene, andTetralin, tetrahydronaphthalene (Ciel-In), have good lubricatingcharacteristics. Decalln has a boiling point of 379 F. and a freezingpoint below 55 F. Tetralin has a boiling point of 404 F. and a freezingpoint below -40 F. Both of these are col-' orless liquids and havebetter lubricating characteristics than a neutral mineral oil lubricant,that is a neutral oil having a viscosity of 100 at 100 F. However,alt-1% of one of the well known extreme pressure additives is added toTetralin and Decalin, lubricants of high loadcarrying characteristicswill be formed.

With these viscosity values it is apparent that the viscositytemperature curves are practically fiat and therefore there is littlechangein' the temperature range in which a lubricant ordinarily isoperative. Due to the fact that the viscosities are so lowat. the lowtemperatures, Tetralln and Decalin are well adapted for low temperaturelubrication, v

Decalin andTetralin are compatible with the alkali and alkaline earthmetal with Tetralin or Decalin to produce satisfactory greases. It ispreferred furthermore'to add an extreme pressure additive to theTetralin or Decalin before they are blended with the soap in making thegreases; for example, from 0.1% to 1% of the additive, thereby producinggreases having extreme pressure load-carrying characteristics.

Tetralin and'Decalin have a tendency to oxidize but it has been foundthat if a small proportion of from .01% to 0.1% of one of they/e11 knownantioxidants is dissolved in the Tetralin or Decalin they become verystable. For example from .01 to .1% of hydroquinone, py ogallol, ora-naphthol are very efiective -antioxidants for stabilizing Decalin andTetralin.

The extreme pressure additives which may be i used with Tetralin andDecalin may be any of the well known additives that are commonly usedfor treatment of mineral oil lubricants. A small proportion of theextreme pressure additive or agent, for example, from 0.1% to 1%, isefi'ective to impart extreme pressure properties to the lubricant.Polane, a commercial extreme pressure agent which is known aschlormethyl stearate may be used. Tricresyl phosphite or a ,mixture oftricresyl phosphite and tricresyl phosphate are efi 'ective additives.The sulfurized tricresyl phosphine extreme pressure agents described inEngelke Patent No. 2,260,303, granted October 28, 1941, may be used, asalso the suliurized tin salts of alkyl phenol. carboiwlic acids asdescribed in Patents Nos. 2,197,834-5; 2,256,- l il; and 2,257,751.

When making the greases the extreme pressure additive and theantioxidant are dissolved in Decalin or Tetralin, and then the treatedhydronaphthalenes are blended with the soaps of lithium, calcium, oraluminum. Preferably the aluminum soap is used in conjunction with thecal- I cium or lithium soaps. A preferred product comprises from 4% to15% of lithium stearate,

soaps for the pro duction of greases which stay in stable emulsion.

The lithium, calcium andaluminum soaps are mutually soluble in Tetralinand Decalin. Preferably the metal soaps are stearates but the oleatesand palmitates will blend with Decalin to.

form good greases. It has beenfound that from x 4 to 20% of these metalsoaps maybe blended from 1% to 3% of aluminum stearate, from 0.1% to 1%of Polane," from 0.01% to'0.1% of pyrogallol, the remainder-of theproduct consisting essentially of Decalin or Tetralin. Other greases maybe made containing from 4% to 20% of a metalsoap of a. fatty acid suchas lithium stearate or one of the other soaps mentioned above,

the remainder of such greases consisting essentially of DecalinorTetralin. These greases may contain asmall proportion of anantloxidant'or a small proportion of an extreme pressure agent, or both.

Decalin and Tetralin may be mixed together in I ium stearate.

most any desired proportion forum as a lubricant. or for use in makinga. grease which may contain from 4% to 20% of a soap such as lith-Decalin and Tetralin are formed by the hydrogenation of naphthalene. Thehydrogenation of naphthalene to form Decalincan be carried out to formisomeric compounds, the cisand trans- Decalins. Each of these isomersmay be used as a lubricant. All of the polyhydronaphthalenes tested havebeen found to have lubricating properties, and the extreme pressureadditives are soluble in all of the polyhydronaphthalenes to provide:extreme pressure lubricants. The po1yhydronaphthalene lubricants maycontain from 0.1% to 1% of .an extreme pressure agent, or from 0.01% to0.1% of an antioxidant, or both an extreme pressure agent andanantioxidant in about these proportions.

The preferred form of the invention havin been thus described, what isclaimed as new is:

1. A low temperature lubricant consisting es-' asazrro 4. A lowtemperature lubricant consisting essentially or Tetralln havingdissolved therein a small proportion of an extreme pressure agentsuiiicient to impart extreme pressure properties to the lubricant.

5. A low temperature lubricant consisting essentially or a mixture ofDeealin and Tetralin having dissolved therein a small proportion of anextreme pressure agent suficlent to impart extreme pressure propertiesto the lubricant.

6. A low temperature lubricant comprising from about 4% to 20% of a.metal soap of a fatty acid, the. remainder of the lubricant consistingessentially of Decalin.

7. A low temperature lubricant comprising from about 4% to 20% of ametal soap of a fatty acid, the remainder of the lubricant consistingessentially of Tetralin.

8. A low temperature lubricant comprising from about 4% to 20% oflithium stearate, the

remainder of the lubricant consisting essentially I of Decalin.

sentlallyof a polyhydronaphthalene having dlssolved therein a smallproportion of an extreme pressure agent sufilcient to impart extremepressure properties to the lubricant.

2. A low temperature lubricant consisting essentially of apolyhydronaphthalene having dissolved therein a-smali proportio'n'of anextreme pressure agent and a small proportion of an antioxidant, saidagent and antioxidant being present in suillcient proportion torespectively impart extreme pressure properties to the lubricant and toprotect the lubricant against oxidation.

3. A low temperature lubricant consisting essentially of Decalin havingdissolved therein a small proportion of an extreme pressure agentsuflicient to impart extreme'pressure properties to the lubricant.

mainder oi the lubricant consisting essentially of Decalin.

' JOHN D. MORGAN.

